Masonry water repellent composition



maintain the water repellent.

U e i MASONRY WATER vREPELLENT COMPDSITION" CONTAINING POLYSILOXANE MIXTURE AND METHOD OF MAKING SAME James D. Lyons and Barber C. Carlson, iMidland, Mich.,- assignors to Dow Corning Corporation, Midland, Mich.', a corporation oiMichigan I i A I J No Drawing. Application November 4, 1957 Serial No. 694,102

2 Claims. (Cl. 260-42) This application relates to silicone compositions especially designed for Water repellent coatings on masonry. Silicones have been used to render masonry water repellent for many years. The heretofore employed silicones have met with considerable commercial success:

85% by weight of a me'thylsiloxane having the composition of-from.65 to 80 mol percent monomethylsiloxane, from 15 to30 mol-percent dimethylsiloxane and not more than 5 mol percent trimethylsiloxane, said siloxane 1) containing from 1 to 12% by weight silicon-bonded methoxy groups and v(2) from 15 to by weight of monopropylsiloxane containing from 15 to 60% by. weight silicon-bonded ethoxy groups.

Applicants have found that the above combination of methyl and propylsiloxane containing the respective amounts of methoxy and ethoxy groups give the best overall performance on'masonry of any known silicone water repellent. It has also been found that when any of the above critical limitations are exceeded, inferior performance is obtained.

Siloxane (1) employed in this invention can be either a methoxylated copolymer of monomethylsiloxane and dimethylsiloxane or it can ,be a methoxylated copolymer of monomethylsiloxane, dimethylsiloxane, or-trimethylsiloxane. mixture of methylchlorosilanes with a mixture of water and methanol, in which the water is present in amount less than the theoretical required to hydrolyze all of the chlorine in the chlorosilanes. It is best to have a suitable solvent such as xylene or toluene present during the hydrolysis.

Siloxane (2) is best prepared by hydrolyzing propyltrichlorosilane in a mixture of ethanol, water and a suitable solvent such as xylene or toluene, in which the amount of water is less than the theoretical amount required to react with all of the chlorine.

After preparation, the alkoxylated siloxanes are then blended in the desired proportions. They can be diluted out to a desired concentration for use on masonry. Suitable solvents for such dilution are toluene, xylene, mineral spirits and chlorinated hydrocarbons. The siloxane can be applied to the masonry with any concentration, but the preferred concentration is from 2 to 5%.

It should be understood that the compositions of this invention can be employed for other uses such as the Siloxane (l) is best prepared by reacting a materials;

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water repelling of fabrics and in thepreparation of coat- 0 ing compositions.

The term masonry building andsurfacing materials as brick, concrete, cinder block, mortar, tile, stone, stucco and equivalent lnthe absorption to place a 2-inch cube-of material in water which is Mi-lHCILdBCP- .The weightof waterabsorbed during given interval of time was then measured.

EXAMPLE 1 A mixtureof (1) 75% "by weight of a copolymer of 75 mol percent monomethylsiloxane, 24 mol percent dimethylsiloxane, and 1 mol percent trimethylsiloxane, which'copolymer contained 8% by weight silicon-bonded methoxy groups was mixed with (2) 25% by weight of a monopropylsiloxane containing 18.4% by weight silicon-bonded ethoxy groups. The mixed siloxanes were diluted with naphthol mineral spirits to give a concentration of 5% by weight combined siloxane. The solution was applied to various types of masonry and in each case the masonry was allowed to air dry for 24 hours and the water absorption and contact angle was determined. The results are shown in the table.

Table I Water Absorption in percent by wt. Contact Type Masonry Angle.

24 hrs. 12 hrs.

Cement cubes .49 85' Very good. Chicago common brick. 03 08 Do. Mortar 75 1. 2

In addition, the solution of the siloxane was applied to a brick wall. The water repellency of the treated wall cone masonry water repellents.

EXAMPLE 2 A mixture of 75% by weight of siloxane (l) of Example l and 25% by weight of a monopropylsiloxane containing 42.8% by Weightethoxy groups was diluted to 5% by weight total silicone with .naphthol mineral spirits. A solution was applied to mortar and I-Iandley- Roman brick. The materials were .allowed to air-dry for 24 hours and the water absorption was adetermined as before. The results are in the table.

Equivalent results were obtained when amixture of 70% by weight .of a copolymer'of mol percent monomethylsiloxane and 25 mol percent dimethylsiloxane containing 10% by weight silicon-bonded methoxy groups and 30% by weight of a propylsiloxane containing 50% by weight silicon-bonded ethoxy groups, is applied to masonry in accordance with the procedure of Example 1.

That which is claimed is: l. A composition of matter consisting essentially of Patented Mari 8,111960 as employed herein includes such' tests: given below the procedure was 3 a mixture of (1) .from .65 to 85 by weight of a methylsiloxane having a composition of from 65 to 80 mol percent monomethylsiloxane, from to mol percent dimethylsiloxane and up to 5 mo1 percent trimethylsiloxane, said siloxane 1) containing from 1 to 12% by weight silicon-bonded methoxy groups and (2) from 15 to 'by weight of a monopropylsiloxane containing from 15 to by weight silicon-bonded ethoxy groups.

2. A method of rendering masonry water repellent comprising applying to the masonry an organic solvent solution of a mixture of .(1) from to 85% by weight of a methylsiloxane having a composition of from 65 to mol percent monomethylsiloxane, from 15 to 30 mol percent dimethylsiloxane and up to 5 mol percent trimethylsiloxane, said siloxane (1') containing from 1 to 12% by weight silicon-bonded methoxy groups and (2) from 15 to 35% by weight of a monopropylsiloxane containing from 15 to 60% by weight silicon-bonded ethoxy groups, and thereafter allowing" the masonry to dry.

Referenses Cited in the file of'this patent UNITED STATES PATENTS 2,5741168 Brick H--. Nov. 6, 1951 2,695,276 Hatcher [Nov. 23, 1954 2,706,723 Bass Apr. 19,1955 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A MIXTURE OF (1) FROM 65 TO 85% BY WEIGHT OF A METHYLSILOXANE HAVING A COMPOSITION OF FROM 65 TO 80 MOL PERCENT MONOMETHYLSILOXANE, FROM 15 TO 30 MOL PERCENT DIMETHYLSILOXANE AND UP TO 5 MOL PERCENT TRIMETHYLSILOXSANE, SAID SILOXANE (1) CONTAINING FROM 1 TO 12% BY WEIGHT SILICON-BONDED METHOXY GROUPS AND (2) FROM 15 TO 35% BY WEIGHT OF A MONOPROPYLSILOXANE CONTAINING FROM 15 TO 60% BY WEIGHT SILICON-BONDED ETHOXY GROUPS. 